With the development of flat panel display (FPD) technique, people have higher and higher requirements on resolution of a display and the refresh rate of a frame. Therefore, there are also urgent needs for developing new material and new techniques. The commonly used conductive metal layer material in current TFTLCDs is aluminum or molybdenum. The advantages of aluminum and molybdenum are simple film-forming process, good adhesion and flatness, soft and unlikely occurrence of climbing break, and little diffusion (film contamination). For a panel with a small size and low resolution, aluminum is the best choice for conductive metal layer material. However, for a large size and high resolution, aluminum becomes not satisfying due to relatively high resistivity. Serving as a conductive metal layer material, the conductivity of copper is far better than aluminum. Therefore, using copper instead of aluminum as conductive metal layer material can improve resolution and brightness of a panel. Meanwhile, frame flickering and line load can be lowered.
Unfortunately, the technique using copper as conductive metal layer material has problems in diffusion and adhesion. In order to solve the problems, as shown in FIG. 1, a barrier layer is commonly added between the conductive metal layer (Cu) and the substrate (generally glass). The barrier layer is formed of copper oxide (CuOx) for blocking the diffusion of copper. As shown in FIG. 2, if the CuOx layer is too thick, the diffusion of oxygen atom would affect the conductivity of copper after annealing at a high temperature. Therefore, it is required to form a relatively thin CuOx layer. As shown in FIG. 3, however, a thin CuOx layer cannot well anchor the Cu conductive metal layer.